1. Field of the Invention
The present invention relates to the field of semiconductor substrate processing equipment. More particularly, the present invention relates to a fluid delivery system that is mounted in close proximity to the chamber and that facilitates the creation of a modular process system design.
2. Background of the Related Art
In the fabrication of integrated circuits, equipment has been developed to automate substrate processing by performing several sequences of processing steps without removing the substrate from a vacuum environment, thereby reducing transfer times and contamination of substrates. Such a system has been disclosed for example by Maydan et al., U.S. Pat. No. 4,951,601, in which a plurality of processing chambers are connected to a transfer chamber. A robot in a central transfer chamber passes substrates through slit valves in the various connected processing chambers and retrieves them after processing in the chambers is complete.
The processing steps carried out in the vacuum chambers typically require the deposition or etching of multiple metal, dielectric and semiconductor film layers on the surface of a substrate. Examples of such processes include chemical vapor deposition (CVD), physical vapor deposition (PVD), and etching processes. Although the present application primarily discusses CVD process chambers and systems, the present invention is equally applicable to other process chambers and systems that utilize a fluid for gas delivery or gas generation.
Process chambers are employed to deposit thin films on semiconductor substrates. The process of depositing the thin films uses a variety of gases provided to the chamber for carrying out the processes. For example, the chambers typically utilize a purge gas such as argon directed to the backside of the edge of the substrate to provide a shield of purge gas that prevents deposition on the edge and backside surfaces of the substrate. In addition, the material to be deposited on the substrate is typically introduced into the chamber suspended in a carrier gas, such as helium. Often the materials used to deposit the films on the substrate are in their liquid phases at room temperature (e.g., DMAH, TEOS, and TDMAT). Thus, to introduce these materials into the process chamber, the material is typically charged in an evaporator so that it becomes mixed with and carried by the carrier gas. One example of an evaporator is a bubbler. In a bubbler, a carrier gas is introduced through a nozzle immersed in the liquid material generating bubbles of the carrier gas that ascend through the liquid. As a result, the liquid material is vaporized into and becomes mixed with the carrier gas and the mixture is introduced into the process chamber for deposition of the material onto the substrate. Other gases are also commonly used in the processing of substrates for example to act as a system purge (e.g., nitrogen) or as a reactant (e.g., hydrogen and oxygen).
As shown in the prior art drawing of FIG. 1, the gas delivery system used to control and deliver the gas to the various process chambers is generally positioned at the back of the system. Therefore, plumbing must be installed to connect each of the process chambers to the gas delivery system. The plumbing typically extends from the gas delivery system beneath the platform to the individual process chambers. Installation and maintenance of the system as well as replacement of any of the system components, therefore, requires substantial manpower due to the substantial plumbing.
In addition, positioning the gas delivery system at the back of the process system necessarily places the controls for the gas delivery a substantial distance from the process chamber, typically an average of about ten feet. Therefore, gas delivery to the chamber (e.g. the time for the gas to reach the chamber from the gas delivery system) may be sensitive to the position of the chamber relative to the gas delivery system which may affect the repeatability of the process and may result in condensation within the system. Further, placing the gas delivery system at the back of the system wastes space and reduces the mobility of the system components hampering interchangeability and flexibility making modular systems less feasible.
Therefore, there is a need to increase the repeatability of the system and to provide a gas delivery system that facilitates interchangeability and a modular design.